Newly Discovered Black Holes Are Largest So Far

Word came this week that scientists at the University of California, Berkeley, have found the two largest black holes known to exist. Each is 10 billion times the size of our sun, and more than 300 million light-years away. Now, we should explain, black holes are known to hold some of the mysteries of our universe. They are so dense, they have so much gravitational pull, that not even light can escape. That makes this discovery all the more remarkable.

Chung-Pei Ma is a professor of astronomy at U.C. Berkeley, and she led the team that published the research, which appears this week in the journal Nature. She joins us on the phone. Thanks so much for being with us.

DR. CHUNG-PEI MA: Thank you very much.

SIMON: So how inadequate was my explanation of black holes, and...

MA: No, that was beautiful. That was exactly what I was going to say, and I have nothing more to add.

SIMON: Well...

MA: We're finished.

SIMON: I like having you on this program, doctor. Let me ask. Now, I understand the previous black hole record holder was only six times the size of our sun. So what makes the one just discovered so large?

MA: Yes. How did these monsters get so big? What did they eat? I mean, somebody was feeding them. And we believe when they were youths, they probably gobbled up lots and lots of gas that was available to them in their parent galaxies. And they got really big and today, they live in very quiet galaxies, in retirement, without much gas. So they were kind of hard to find.

SIMON: That raises this question: How do you find something that is invisible and 300 billion light-years away, in any case?

MA: That's right...

SIMON: And if you say, with great difficulty, I'm going to be very unsatisfied, yes.

(SOUNDBITE OF LAUGHTER)

MA: So by definition, as you said, black holes can't be seen. So we had to use stars very close to the black hole so that they are feeling very strong gravity from the holes. The faster they're moving indicates the stronger the gravity it is; therefore, the more mass of the black hole. We needed to observe the motions of the stars within about 1,000 light-years of the black hole. However, this is 1,000 light-years at a distance of 300 million light-years.

So an analogy will be, this is like squinting at Yo-Yo Ma playing the cello in New York's Carnegie Hall, from Washington, D.C. And then you're trying to measure how fast his fingers are moving while playing "The Flight of the Bumblebee."

SIMON: That's hard.

(SOUNDBITE OF LAUGHTER)

SIMON: Now, these black holes sound so enormous and powerful. Are they anywhere near us? Any reason to worry that there'll be hungry for us, too?

MA: There is actually very good evidence for a black hole in our own galaxy. Still, don't worry. Our own black hole is about 25,000 light-years from us. So I wouldn't get too close, but our solar system is safe so far.